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A device designed to switch between a bank of alkaline batteries and a 9v power adapter. My weather receiver device has a battery and a power adapter. I currently have a SPDT switch to cut between the adapter and battery power, but this causes the arduino to turn off briefly. Here I designed a circuit to cut between the two automatically using a p-channel MOSFET. It effectively is a battery isolator that cuts the battery off entirely when power is on.

I initially thought using schottky diodes would do the trick, but that arrangement has the disadvantage that any voltage difference between the battery and the DC source would cause the current to flow from the battery through the load. Since 9v batteries are usually at 9.6 volts, this means they’d drain to roughly 9v over time to match the power source. The diodes aren’t perfect, and a little current leaks through below their forward voltage. Will update when the circuit is tested. I’m aiming for a capacity under 1A to run an arduino and some accessories.

This is an Arduino powered wireless weather station that measures temperature, humidity, pressure, wind speed, and direction. It uses ISM radio and has WIFI capability. Feel free to use these diagrams for your own projects, or to expand on them.

Full-Paper

The late-run Kenai River chinook salmon Oncorhynchus tshawytscha, which are managed under
the principle of maximum sustained yield (MSY) have experienced declines in run size in recent
years. Several runs in the past ten years have not met the lower end of escapement goals. Alaska
Department of Fish and Game sets escapement goals that use the Ricker stock-recruitment model
as their basis. The historical vital rate parameters deduced from records form the basis for these
calculations. In this paper, I create a model that uses historical variation in vital rates to simulate
late-run chinook runs for 20-year periods in the future using recorded average harvest rates, and
a theoretical lower harvest scenario. From the simulations, the median number of lower
escapement failures is 2 per 20 year period for both a normal and reduced harvest scenario. No
significant differences were found between the mean escapements of both harvest scenarios. The
results of this model suggest that manipulating harvest levels alone will not significantly improve
escapement, and that other factors in chinook life history will need to be improved to achieve
that goal.